Reducing Hall

[Dr.Future]

SE Electronics "Reflexion Filter".

[mixer]

No need for expensive stuff, unless you really want to

It may be enough that you build such an absorber yourself out of an old mattress or something similar. Try stuff and you'll realize how it works.

In a similar experiment I and my friend recently fixed a concrete wall home theatre room acoustics by building two sound absorbing elements that were set to the corners of the room next to or behind the front speakers. We built a triangular wooden frame matching the corner and filled it with layers of insulating wool. The insulating wool manufacturer had sound-absorption specifications so it was possible to calculate a bit how it would work in different frequencies, so we sized it to our liking. Simply put thick absorbers will absorb lower frequencies better and thin layers only high and the absorption is related to frequency of sound and absorption factor of the insulator. Resulting elements were 2m high, front panel was 60cm and the wall sides to match to 90 degree corner, filled with insulating wool and then wrapped to black fabric so they looked cool tool. Did not cost much, were easy to build and worked miracles with normal listening volumes, eliminated almost all secondary echoes and hall in speaking volumes too.

[mixer]

I am sorry , I do not have a picture, but what I meant is that you can make a similar device as the commercial one. It does not need to be from all the fancy materials. Thick fabrics absorb sound well. Even brown cardboard box could help a bit. Almost any suitable material placed symmetrically at a close distance around the microphone like the one in the picture would reduce hall somewhat.

What you want is that the speech goes from mouth to the microphone and nowhere else and any wall reflections are directed elsewhere or absorbed. You may need to build suitable fitting or rack yourself. Also you may need to alter the microphone orientation with the absorber/reflector so that the absorber is between the big space and mic, instead of between the mic and the closest wall. Test what works best.

The absorber furniture that we built was an example how to reduce standing waves and echos in the room by building separate furniture that absorbs sound.

[Vosla]

Some guy had the idea to hang some cloth on the walls plus a kind of miniscreen behind the microphone. That reduced stray echos by some amount with almost zero costs and minimal effort to fix the cloth to the wall (simple pins if I recall correctly).

[Vosla]

Sorry. By cloth I ment simply woven fabric - (Stoff - umso dicker, umso besser)